1. Field of the Invention
The present invention relates to wireless communications, and more particular, to a method and apparatus for transmitting a reception acknowledgment for hybrid automatic repeat request (HARQ) in a wireless communication system.
2. Discussion of the Related Art
Long term evolution (LTE) based on 3rd generation partnership project (3GPP) technical specification (TS) release 8 is a promising next-generation mobile communication standard.
As disclosed in 3GPP TS 36.211 V8.7.0 (2009-05) “Evolved Universal Terrestrial Radio Access (E-UTRA); Physical Channels and Modulation (Release 8)”, a physical channel of the LTE can be classified into a downlink channel, i.e., a physical downlink shared channel (PDSCH) and a physical downlink control channel (PDCCH), and an uplink channel, i.e., a physical uplink shared channel (PUSCH) and a physical uplink control channel (PUCCH).
The PUCCH is distinguished by using different codes, frequencies, times, or combinations thereof while using the same time-frequency resources. Code division multiplexing (CDM) uses different codes. Frequency division multiplexing (FDM) uses different frequencies. That is, each of user equipments transmits its PUCCH by using different codes and/or frequencies in the same time resource.
Meanwhile, a single-carrier system generally considers only one carrier even if a different bandwidth is set between an uplink and a downlink. The carrier is defined with a center frequency and a bandwidth. A multiple-carrier system uses a plurality of component carriers (CCs) having a narrower bandwidth than a full bandwidth.
The multiple-carrier system can support backward compatibility with respect to legacy systems, and can significantly increase a data rate by using multiple carriers.
The 3GPP LTE system is a single-carrier system supporting only one bandwidth (i.e., one CC) among {1.4, 3, 5, 10, 15, 20} MHz. On the other hand, an LTE-advanced (LTE-A) which is an evolution of 3GPP LTE employs multiple carriers.
In the single-carrier system, a control channel and a data channel are designed on the basis of a single carrier. However, it may be ineffective if the channel structure of the single-carrier system is also used in the multi-carrier system without alteration.